Ionic force

Ionic Strength, I - measure in the solution of interstitial interactions, determining the influence of all the ions present on their behavior and interaction with the electric field. For simple 1: 1 electrolytes containing only monovalent ions, eg, HCl, NaOH or NaCl, the ionic strength is equal to their molar concentration, whereas the ionic strength for the 2: 2 electrolyte, eg MgSO4, is four times greater than its concentration. >

ionic strength: I = 1 2 ∑ i = 1 n c i from i 2 {\displaystyle I={\begin{matrix}{\frac {1}{2}}\end{matrix}}\sum _{i=1}^{n}c_{i}z_{i}^{2}}

where: Ci - ion concentration (mol / dm) or molar [mol / kg], ionic charge, n - total number of ion species in solution.

The direct influence of ionic strength is manifested, among others. in the change of the so-called. The activity coefficients f (often used as the symbol γ). For example, the increase in ionic strength resulting in a decrease in activity coefficients causes certain ions to behave as if they were less, ie less active, ai = cifi. The influence of ionic strength on activity coefficients is most often described using the Debye-Hückel equation.

The salt effect of increasing the solubility of the sparingly soluble salt due to the addition of another salt which does not form with the ions of the first complex salt or other sparingly soluble salts is due to a decrease in the activity coefficients. This is a change in the so-called. The concentration of the solubility of the salt, while the thermodynamic product of solubility expressed by ionic activity remains independent of the concentrations of other ions and molecules in solution. A similar effect is observed for concentration dissociation (acidification) of acids and bases.

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